Predictive values for different cancers and inflammatory bowel disease of 6 common abdominal symptoms among more than 1.9 million primary care patients in the UK: A cohort study

Author summary Why was this study done? The assessment of patients who present with abdominal symptoms in primary care is challenging. Abdominal symptoms are responsible for about 1 in 10 consultations but can relate to many underlying pathologies; predictive values for individual diseases are low. Prolonged intervals to diagnosis of cancer (often presenting with abdominal symptoms) and inflammatory bowel disease (IBD) are common and associated with worse patient outcomes. When cancer is suspected in patients with abdominal symptoms, several possible sites need to be considered, requiring different diagnostic modalities What did the researchers do and find? Using anonymous data from primary care records in the UK, we examined the predictive value of 6 common abdominal symptoms for cancer (overall and for specific cancer sites) and for IBD. Change in bowel habit and rectal bleeding had the highest positive predictive values (PPVs) for colon and rectal cancer; dysphagia for esophageal cancer; and abdominal bloating/distension (in women) for ovarian cancer. The highest PPVs for abdominal pain (either sex) and abdominal bloating/distension (men only) related to non-abdominal cancer sites. For diagnosis of either cancer or IBD, the predictive values of rectal bleeding exceeded guideline-recommended risk thresholds for specialist referral in all age-sex strata, as did the predictive values of abdominal pain, change in bowel habit, and dyspepsia, in those aged 60 years and over. What do these findings mean? Specialist referral decisions can be made considering the predictive values of common abdominal symptoms for cancer alongside that for IBD and the composite outcome of either cancer or IBD. Jointly assessing the risk of cancer or IBD can better support decision-making and prompt diagnosis of both conditions, enabling specialist referrals or investigations, particularly of women. Investigation strategies and use of diagnostic modalities can be guided by the stratification of risk of different abdominal symptoms for different cancers sites. Background The diagnostic assessment of abdominal symptoms in primary care presents a challenge. Evidence is needed about the positive predictive values (PPVs) of abdominal symptoms for different cancers and inflammatory bowel disease (IBD). Methods and findings Using data from The Health Improvement Network (THIN) in the United Kingdom (2000-2017), we estimated the PPVs for diagnosis of (i) cancer (overall and for different cancer sites); (ii) IBD; and (iii) either cancer or IBD in the year post-consultation with each of 6 abdominal symptoms: dysphagia (n = 86,193 patients), abdominal bloating/distension (n = 100,856), change in bowel habit (n = 106,715), rectal bleeding (n = 235,094), dyspepsia (n = 517,326), and abdominal pain (n = 890,490). The median age ranged from 54 (abdominal pain) to 63 years (dysphagia and change in bowel habit); the ratio of women/men ranged from 50%/50% (rectal bleeding) to 73%/27% (abdominal bloating/distension). Across all studied symptoms, the risk of diagnosis of cancer and the risk of diagnosis of IBD were of similar order of magnitude, particularly in women, and younger men. Estimated PPVs were greatest for change in bowel habit in men (4.64% cancer and 2.82% IBD) and for rectal bleeding in women (2.39% cancer and 2.57% IBD) and lowest for dyspepsia (for cancer: 1.41% men and 1.03% women; for IBD: 0.89% men and 1.00% women). Considering PPVs for specific cancers, change in bowel habit and rectal bleeding had the highest PPVs for colon and rectal cancer; dysphagia for esophageal cancer; and abdominal bloating/distension (in women) for ovarian cancer. The highest PPVs for abdominal pain (either sex) and abdominal bloating/distension (men only) related to non-abdominal cancer sites. For the composite outcome of diagnosis of either cancer or IBD, PPVs of rectal bleeding exceeded the National Institute of Health and Care Excellence (NICE)-recommended specialist referral threshold of 3% in all age-sex strata, as did PPVs of abdominal pain, change in bowel habit, and dyspepsia, in those aged 60 years and over. Study limitations include reliance on accuracy and completeness of coding of symptoms and disease outcomes. Conclusions Based on evidence from more than 1.9 million patients presenting in primary care, the findings provide estimated PPVs that could be used to guide specialist referral decisions, considering the PPVs of common abdominal symptoms for cancer alongside that for IBD and their composite outcome (cancer or IBD), taking into account the variable PPVs of different abdominal symptoms for different cancers sites. Jointly assessing the risk of cancer or IBD can better support decision-making and prompt diagnosis of both conditions, optimising specialist referrals or investigations, particularly in women.